fSpy starting problems 2.8+?
Don't... download the entire repository.

Download the latest fspy binary from here: github.com/stuffmatic/fSpy/releases
And the latest add-on for blender from here: github.com/stuffmatic/fSpy-Blender/releases.


For Linux (AppImage): Right-click (RMB) the Binary &gt; Permissions &gt; Allow executing file, which should work for all distros.
Further reading: How to download and install an add-on hosted on github properly?